Xenon recovery and purification device for anesthetic gas mixture and intelligent control system

Abstract

The present application relates to the technical field of xenon recovery control, and particularly relates to a xenon recovery and purification device for anesthetic mixed gas and an intelligent control system. The device comprises a data acquisition module for acquiring gas state data of each molecular sieve tower in real time; a processing control unit for determining a xenon migration index based on the pressure in the tower and the xenon migration amount of each molecular sieve tower at any time; determining a switching urgency according to the gas concentration change characteristics and the feed flow rate fluctuation characteristics; generating a comprehensive switching degree in combination with the xenon migration index and the switching urgency; monitoring the change trend of the comprehensive switching degree over time in real time to determine a change rate; determining the best switching time when the change rate is first lower than a preset convergence threshold; and a switching module for triggering a double molecular sieve tower mode switching at the best switching time, thereby significantly improving the xenon purification efficiency of the device.

Description

Technical Field

[0001] This invention relates to the field of xenon recovery and control technology, specifically to a xenon recovery and purification device and intelligent control system for anesthetic mixed gases. Background Technology

[0002] Xenon (Xe) is widely used in the field of anesthesia, especially in certain high-risk surgeries. During the use of anesthetic gases, xenon is often mixed with other anesthetic gases (such as nitrogen and oxygen). The recovery and purification process requires efficient separation and control to ensure the purity of the xenon and enable its reuse.

[0003] Currently, in existing technologies, when purifying xenon in anesthesia mixtures using recovery and purification devices, the xenon is purified by continuously switching the adsorption-desorption modes of a dual molecular sieve tower. Current dual-tower dual molecular sieve towers continuously purify xenon using a fixed switching rhythm. However, because the inlet rate of the anesthetic mixture and the adsorption / desorption capacity of the molecular sieve towers change with the operation of the device, the fixed switching rhythm lacks real-time sensing and dynamic response capabilities to various changes occurring in the device. This leads to uneven workload on the molecular sieve towers and insufficient utilization of the adsorbent within the molecular sieve towers, affecting the purity of the xenon. Summary of the Invention

[0004] To address the technical problem that a fixed switching rhythm affects the purity of xenon gas, this invention provides a xenon gas recovery and purification device and an intelligent control system for anesthetic gas mixtures. The specific technical solution adopted is as follows:

[0005] This invention proposes a xenon gas recovery and purification device for anesthetic gas mixtures. The xenon gas recovery and purification device includes two parallel molecular sieve towers, wherein the dual molecular sieve towers alternately switch between adsorption and desorption modes during operation. The device includes:

[0006] The data acquisition module is used to acquire gas state data of each molecular sieve column in real time. The gas state data includes the pressure inside the column, gas concentration, and feed flow rate.

[0007] The processing and control unit is used to determine the xenon migration amount of each molecular sieve column at any given time based on the pressure inside the column and using an adsorption isotherm model; to determine the xenon migration index of each molecular sieve column at any given time based on the pressure change characteristics and xenon migration amount of each molecular sieve column at any given time, which is used to characterize the degree of xenon adsorption or desorption inside the column; to determine the switching urgency of each molecular sieve column at any given time based on the gas concentration change characteristics and feed flow rate fluctuation characteristics; to generate a comprehensive switching degree based on the xenon migration index and switching urgency; to monitor the change trend of the comprehensive switching degree over time in real time and determine the rate of change; when the rate of change first falls below a preset convergence threshold, it is determined to be the optimal switching time;

[0008] The switching module is used to trigger the switching of the dual molecular sieve tower mode at the optimal switching time.

[0009] Furthermore, the xenon gas recovery and purification device for the anesthetic gas mixture also includes:

[0010] Obtain the initial moment when each molecular sieve column just enters the adsorption or desorption mode, and the initial pressure inside each molecular sieve column at the initial moment.

[0011] The pressure change index of each molecular sieve column at any time is obtained by calculating the ratio of the pressure inside the column at any time to the initial pressure at the target initial time. The target initial time is used to indicate the initial time that is the shortest in time interval from any time.

[0012] If the pressure change index exceeds the preset adsorption threshold, the corresponding molecular sieve tower is determined to be in adsorption mode, and the molecular sieve tower in adsorption mode is called an adsorption tower.

[0013] If the pressure change index is less than the preset adsorption threshold, the corresponding molecular sieve tower is determined to be in desorption mode, and the molecular sieve tower in desorption mode is called a desorption tower.

[0014] Furthermore, the process for determining xenon migration includes:

[0015] Obtain the partial pressure of xenon gas inside each molecular sieve column;

[0016] For the adsorption tower, based on the partial pressure of xenon gas inside the tower, the amount of xenon adsorbed in the adsorption tower at any time is calculated using the adsorption isotherm model; the amount of xenon adsorbed is used as the amount of xenon migration in the adsorption tower.

[0017] For the desorption tower, based on the partial pressure of xenon gas inside the tower, the amount of xenon desorption at any time is calculated using the adsorption isotherm model; the amount of xenon desorption is used as the amount of xenon migration in the desorption tower.

[0018] Furthermore, the process of determining xenon migration indicators includes:

[0019] Obtain the maximum adsorption capacity and maximum desorption capacity of each molecular sieve column;

[0020] For the adsorption tower, the ratio of the xenon migration amount at any time to the maximum adsorption capacity of the adsorption tower is calculated to obtain a first ratio of the adsorption tower at any time; for the desorption tower, the ratio of the xenon migration amount at any time to the maximum desorption capacity of the desorption tower is calculated to obtain a second ratio of the desorption tower at any time.

[0021] Calculate the product of the first ratio and the pressure change index, and use it as the xenon migration index of the adsorption tower at any time.

[0022] Based on the second ratio and pressure change index, the xenon migration index of the desorption tower at any time is obtained through a preset index calculation function.

[0023] Furthermore, the process of determining the urgency of the switch includes:

[0024] For the adsorption tower, the standard output concentration of other gases in the adsorption tower at any time, the first gas concentration when the other gases flow out of the adsorption tower, and the second gas concentration when the other gases enter the adsorption tower are obtained; for the desorption tower, the third gas concentration when xenon gas flows out of the desorption tower and the fourth gas concentration when xenon gas enters the desorption tower at any time are obtained, wherein, other gases are used to indicate other gases besides xenon in the mixed gas.

[0025] Based on the standard output concentration, the first gas concentration, and the second gas concentration, the first switching evaluation score of the adsorption tower at any time is obtained through a preset scoring calculation function.

[0026] Calculate the absolute difference between the concentration of the third gas and the concentration of the fourth gas, and use the negative of the absolute difference as the second switching evaluation score of the desorption tower at any time.

[0027] The rate of change of flow rate of each molecular sieve column is obtained by calculating the ratio of the feed flow rate of the mixed gas at any time to the feed flow rate of the mixed gas at the next previous time.

[0028] The product of the first switching assessment score and the flow rate change rate of the adsorption tower is calculated as the switching urgency of the adsorption tower; the product of the second switching assessment score and the flow rate change rate of the desorption tower is calculated as the switching urgency of the desorption tower.

[0029] Furthermore, the process of determining the overall handover degree includes:

[0030] Calculate the sum of the positive integer 1 and the switching urgency of the adsorption tower, and use it as the first weight; calculate the sum of the positive integer 1 and the switching urgency of the desorption tower, and use it as the second weight.

[0031] The product of the xenon migration index and the first weight is calculated as the comprehensive switching degree of the adsorption tower at any time; the product of the xenon migration index and the second weight is calculated as the comprehensive switching degree of the desorption tower at any time.

[0032] Furthermore, the process of determining the rate of change includes:

[0033] Calculate the absolute difference between the overall switching degree of the adsorption tower at any given time and the overall switching degree of the adsorption tower at the next preceding time, and use this as the first difference of the adsorption tower at the corresponding time.

[0034] Calculate the absolute difference between the overall switching degree of the desorber at any given time and the overall switching degree of the desorber at the next preceding time, and use this as the second difference of the desorber at the corresponding time.

[0035] Calculate the product of the first difference and the second difference at the same time point as the rate of change, where the rate of change is a normalized value.

[0036] Furthermore, the switching module also includes:

[0037] At the optimal switching point, the adsorption and desorption modes of the dual molecular sieve tower are exchanged by gradually adjusting the pressure and controlling the intake valve to switch the direction of the mixed gas flow.

[0038] Furthermore, the xenon gas recovery and purification device for the anesthetic gas mixture also includes:

[0039] The composition and concentration of the gas at the outlet of the desorption tower are monitored in real time. When the xenon concentration in the outlet gas is not less than the preset xenon concentration threshold and the oxygen concentration is not greater than the preset oxygen impurity threshold, the xenon purification of the xenon recovery and purification device is determined to be complete.

[0040] An intelligent control system for the recovery and purification of xenon in an anesthetic gas mixture is disclosed. The intelligent control system includes a memory, a processor, and a computer program stored in the memory and running on the processor. When the processor executes the computer program, it implements the steps of the xenon recovery and purification device for the anesthetic gas mixture.

[0041] The present invention has the following beneficial effects:

[0042] This invention utilizes an adsorption isotherm model to analyze the adsorption or desorption capacity of a molecular sieve tower, and corrects for adsorption or desorption capacity by incorporating pressure changes. This allows for precise quantification of the real-time operating status of the molecular sieve tower using a xenon migration index, facilitating the more accurate determination of the optimal switching time. Furthermore, considering that gas concentration and feed rate also affect the xenon purification effect, the invention further integrates gas concentration difference characteristics and feed rate fluctuation characteristics to generate a switching urgency. This switching urgency is then combined with the xenon migration index to determine the comprehensive switching degree. Finally, the optimal switching time is determined by utilizing the property that the comprehensive switching degree gradually converges over time. Switching to the dual molecular sieve tower mode at the optimal switching time significantly improves the xenon purification efficiency and purity of the device, effectively avoiding the problems of unsaturated adsorption or incomplete desorption caused by traditional fixed-cycle switching. Attached Figure Description

[0043] To more clearly illustrate the technical solutions and advantages in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0044] Figure 1 A schematic diagram of the mechanical structure of a conventional xenon gas recovery and purification device for anesthetic mixed gas provided for an embodiment of the present invention;

[0045] Figure 2 This is a schematic diagram of the electrical composition of a xenon gas recovery and purification device for anesthetic mixed gas provided in an embodiment of the present invention;

[0046] Figure 3 This is an example diagram of the adsorption and desorption modes provided in one embodiment of the present invention;

[0047] Figure 4 This is a schematic diagram of the data processing process of a xenon gas recovery and purification device for anesthetic mixed gas provided in an embodiment of the present invention.

[0048] Figure 3 The label is denoted as:

[0049] A represents feed valve A; B represents feed valve B; C represents exhaust valve C; D represents exhaust valve D. Detailed Implementation

[0050] To further illustrate the technical means and effects adopted by the present invention to achieve its intended purpose, the following, in conjunction with the accompanying drawings and preferred embodiments, details the specific implementation, structure, features, and effects of a xenon gas recovery and purification device and intelligent control system for anesthetic mixed gases proposed according to the present invention. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0051] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0052] The following description, in conjunction with the accompanying drawings, details the specific solution of a xenon gas recovery and purification device and intelligent control system for anesthetic mixed gases provided by the present invention.

[0053] Please see Figure 1The diagram illustrates a schematic mechanical structure of a conventional xenon recovery and purification device for anesthetic mixed gases according to an embodiment of the present invention. The xenon recovery and purification device includes two parallel molecular sieve towers, A and B. The xenon recovery and purification device also includes other common components, such as a radiator, a flow meter, and a xenon concentration sensor. Under normal circumstances, the dual molecular sieve towers alternately switch between adsorption and desorption modes during operation, and the treated mixed gas (containing xenon, oxygen, and nitrogen) enters molecular sieve tower A. Because the sieve material in molecular sieve tower A has a stronger adsorption capacity for xenon, xenon is firmly adsorbed onto the surface of the adsorbent, while oxygen and nitrogen, due to their weaker adsorption capacity, are directly discharged from the top of molecular sieve tower A. Then, when the adsorption capacity of the sieve material in molecular sieve tower A approaches saturation, the device automatically switches valves: the mixed gas then enters molecular sieve tower B (repeating the adsorption process of molecular sieve tower A to ensure uninterrupted separation); simultaneously, molecular sieve tower A enters desorption mode, causing the adsorbed xenon to desorb from the surface of the sieve material in molecular sieve tower A, and the desorbed gas is collected in a storage tank; alternating switching occurs: after molecular sieve tower B becomes saturated, it switches back to adsorption in molecular sieve tower A and desorption in molecular sieve tower B, repeating this process to achieve continuous xenon processing. The processes of separating the mixed gas and purifying xenon in the xenon recovery and purification device for anesthetic mixed gases are existing technologies and will not be described in detail in this embodiment.

[0054] like Figure 2 As shown, the xenon gas recovery and purification device for anesthetic mixed gas includes a data acquisition module, a processing control unit, and a switching module. The data acquisition module and the processing control unit are connected, and the switching module is controlled by the processing control unit.

[0055] The data acquisition module is used to acquire gas state data of each molecular sieve column in real time. The gas state data includes the pressure inside the column, gas concentration, and feed flow rate.

[0056] It should be noted that the xenon recovery and purification device includes two parallel molecular sieve towers, in which the adsorption mode and desorption mode are alternately switched during operation.

[0057] The data acquisition module needs to be positioned as close as possible to the bimolecular sieve tower, without affecting the gas flow inside the xenon recovery and purification device used for anesthetic gas mixtures, in order to accurately monitor gas state data. Therefore, the data acquisition module can utilize miniaturized detection devices and transmit data to the data processor wirelessly. For example, the data acquisition module can be equipped with a low-power wireless communication module such as Bluetooth, and the data processor can also be equipped with a similar wireless communication module, eliminating the need for signal transmission lines and further avoiding interference with the normal operation of the xenon recovery and purification device while reducing power consumption. Accordingly, the data acquisition module needs a dedicated power supply, which can be a miniature power source such as a button battery to reduce size and further avoid affecting the normal operation of the xenon recovery and purification device.

[0058] For example, for a bimolecular sieve column, the adsorption and desorption modes are illustrated in the following diagram. Figure 3 As shown, where, Figure 3 The dashed line is used to indicate the direction of the anesthetic gas mixture flow. Figure 3 The designation A represents feed valve A, designation B represents feed valve B, designation C represents exhaust valve C, and designation D represents exhaust valve D. Figure 3 Feed valve A is connected to molecular sieve tower E, and feed valve B is connected to molecular sieve tower F. Exhaust valves C and D correspond to the exhaust ports of molecular sieve towers E and F, respectively. Molecular sieve tower E is in adsorption mode, and molecular sieve tower F is in desorption mode. The mixed gas enters molecular sieve tower E through the pipeline. Xenon gas is adsorbed on the sieve material inside molecular sieve tower E, while other gas molecules enter molecular sieve tower F. At this time, molecular sieve tower F is in desorption mode. The sieve material inside molecular sieve tower F releases the adsorbed xenon gas, and the other gases and the desorbed xenon gas form a purified gas stream for output.

[0059] It should be noted that the feed flow rate is used to indicate the flow rate of the mixed gas entering the molecular sieve tower. The specific method for determining the feed flow rate is a well-known technique to those skilled in the art, and will not be described in detail in this embodiment. For example, the feed flow rate can be determined by measuring the mass flow rate of the mixed gas through a flow meter installed on the mixed gas feed pipe, such as a Coriolis mass flow meter. Then, the feed flow rate can also be corrected by a temperature compensation formula.

[0060] The processing and control unit is used to process gas state data to determine the optimal switching time. The hardware of the processing and control unit can be configured with data processing chips such as CPUs and microcontrollers.

[0061] The switching module is controlled by the processing control unit, including the feed valve group and the exhaust valve group, and is used to trigger the dual molecular sieve tower mode switching at the optimal switching time.

[0062] In this embodiment, at the optimal switching time, the switching module gradually adjusts the pressure and controls the intake valve to switch the direction of the mixed gas flow, thereby exchanging the adsorption and desorption modes of the dual molecular sieve tower.

[0063] It should be noted that the gradual pressure adjustment and intake valve control methods are existing technologies and will not be described in detail in this embodiment.

[0064] For example, for a molecular sieve tower (original adsorption tower) to be switched from adsorption mode to desorption mode: reduce the tower pressure at a rate of 0.05-0.1 MPa / min until the desorption pressure (0.01-0.03 MPa) is reached; during the pressure drop, the nitrogen injection rate is adjusted simultaneously to maintain the gas flow state inside the molecular sieve tower; for a molecular sieve tower (original desorption tower) to be switched from desorption mode to adsorption mode: increase the tower pressure at a rate of 0.08-0.12 MPa / min until the adsorption pressure (0.8-1.2 MPa) is reached; when the pressure difference between the two molecular sieve towers is ≤0.05 MPa, control the inlet valve: close the feed valve and exhaust valve of the original adsorption tower, and simultaneously open the desorption gas exhaust valve and the desorption gas recovery pipeline, wherein the desorption gas recovery pipeline is connected to the gas storage tank; close the desorption gas exhaust valve of the original desorption tower, and simultaneously open the feed valve and exhaust valve.

[0065] The data processing strategy executed by the processing control unit is as follows: Figure 4 As shown, it includes the following steps:

[0066] Step S101: Based on the pressure inside the tower, determine the amount of xenon migration in each molecular sieve tower at any time using the adsorption isotherm model; determine the xenon migration index of each molecular sieve tower at any time based on the pressure change characteristics and xenon migration amount of each molecular sieve tower at any time.

[0067] It should be noted that the xenon migration index is used to characterize the degree of adsorption or desorption of xenon within the tower.

[0068] Adsorption isotherm: Under constant temperature conditions, the relationship curve between the "equilibrium adsorption amount" of an adsorbent for a certain gas and the "equilibrium partial pressure" of that gas on the surface of the adsorbent. The adsorption isotherm model is a well-known technique in the art, and will not be elaborated in this embodiment. For example, the amount of xenon migration at any time in each molecular sieve tower can be determined by the Langmuir model.

[0069] It is important to understand that by continuously changing the pressure inside the molecular sieve tower, the adsorption and desorption modes can be switched. Therefore, pressure changes affect the adsorption and desorption capacity of the sieve material inside the molecular sieve tower. By observing the pressure changes inside the molecular sieve tower, we can further understand the changes in the adsorption and desorption capacity of the sieve material, and it can also be used to analyze the current adsorption or desorption mode of the molecular sieve tower.

[0070] In this embodiment, the initial moment when each molecular sieve column just enters the adsorption or desorption mode and the initial pressure inside each molecular sieve column at the initial moment are obtained; the ratio of the pressure inside each molecular sieve column at any moment to the initial pressure at the target initial moment is calculated to obtain the pressure change index of each molecular sieve column at any moment, wherein the target initial moment is used to indicate the initial moment with the shortest time interval from any moment; if the pressure change index exceeds the preset adsorption threshold, the corresponding molecular sieve column is determined to be in adsorption mode, and the molecular sieve column in adsorption mode is called an adsorption column; if the pressure change index is less than the preset adsorption threshold, the corresponding molecular sieve column is determined to be in desorption mode, and the molecular sieve column in desorption mode is called a desorption column.

[0071] It is understandable that the initial time is used to indicate the moment when the molecular sieve column just enters the adsorption or desorption mode, and the initial pressure is the first stable reading of the pressure sensor when the adsorption or desorption mode is switched.

[0072] Among them, the pressure sensor should be placed as close as possible to the molecular sieve tower, while ensuring that it does not affect the gas flow inside the xenon recovery and purification device used for anesthetic gas mixture, so as to monitor the pressure inside the molecular sieve tower. The pressure sensor can be a small sensor, and the specific model can be set according to actual needs.

[0073] Since if the pressure inside a molecular sieve column at a certain moment is greater than the initial pressure relative to the target initial pressure, it reflects that the molecular sieve column is in adsorption mode. Therefore, the pressure change index can be expressed by the following formula:

[0074]

[0075] in, This represents the pressure change index of the molecular sieve tower at time i. This represents the pressure inside the molecular sieve column at time i. This represents the initial pressure of the molecular sieve column at the target initial time (time 0), where time 0 indicates the initial time that is the shortest in time interval from time 1.

[0076] It should be noted that when the molecular sieve column switches between adsorption and desorption modes, the pressure inside the column needs to be continuously changed to complete the mode switch. Therefore, the initial pressure inside the molecular sieve column cannot be zero at the initial moment. Furthermore, if the pressure at time i is the same as at time o, then... A value of 1 indicates that the molecular sieve tower has just entered the adsorption or desorption mode at time i.

[0077] It should be noted that the specific value of the preset adsorption threshold is determined according to actual needs, and this embodiment does not impose a specific limitation. For example, the preset adsorption threshold can be 1. If the pressure change index of a certain molecular sieve tower exceeds 1 at a certain moment, it is determined that the molecular sieve tower is in adsorption mode at that moment, and the molecular sieve tower in adsorption mode is called an adsorption tower. If the pressure change index of a certain molecular sieve tower is less than 1 at a certain moment, it is determined that the molecular sieve tower is in desorption mode at that moment, and the molecular sieve tower in desorption mode is called a desorption tower. And if the pressure change index of a certain molecular sieve tower is equal to 1 at a certain moment, it is determined that the molecular sieve tower has just switched modes at that moment.

[0078] In this embodiment, the partial pressure of xenon gas inside each molecular sieve column is obtained; for the adsorption column, based on the partial pressure of xenon gas inside the column, the amount of xenon gas adsorbed in the adsorption column at any time is calculated using an adsorption isotherm model; the amount of xenon gas adsorbed is used as the amount of xenon gas migrated in the adsorption column; for the desorption column, based on the partial pressure of xenon gas inside the column, the amount of xenon gas desorbed in the desorption column at any time is calculated using an adsorption isotherm model; the amount of xenon gas desorbed is used as the amount of xenon gas migrated in the desorption column.

[0079] Xenon migration refers to the amount of xenon adsorbed in adsorption mode or the amount of xenon desorbed in desorption mode.

[0080] It should be noted that the specific method of calculating the amount of xenon adsorption and desorption using the adsorption isotherm model based on the partial pressure of xenon gas is a well-known technique in the art, and will not be described in detail in this embodiment.

[0081] It should be noted that since adsorption and desorption are usually reversible processes, the amount of adsorption or desorption at any given time in each molecular sieve column can be collectively referred to as the xenon migration amount. During adsorption, the xenon migration amount is the amount of xenon that migrates from the gas phase to the solid phase, i.e., the adsorption amount; during desorption, the xenon migration amount is the amount of xenon that migrates from the solid phase to the gas phase, i.e., the desorption amount.

[0082] It is important to understand that, in practice, the adsorption or desorption capacity of the sieve material in the molecular sieve tower for xenon is affected by the pressure inside the molecular sieve tower. Furthermore, when the molecular sieve tower switches modes, the pressure inside the tower also changes. Therefore, when investigating the degree of adsorption or desorption of xenon by the molecular sieve tower in a given mode at a certain moment, the pressure change must be taken into account.

[0083] To accurately determine the xenon migration index, the xenon migration index of the adsorption tower is determined based on the xenon migration amount and pressure change index at any time in the adsorption tower; the xenon migration index of the desorption tower is determined based on the xenon migration amount and pressure change index at any time in the desorption tower.

[0084] As an example, the maximum adsorption capacity and maximum desorption capacity of each molecular sieve column are obtained. For the adsorption column, the ratio of the xenon migration amount at any time to the maximum adsorption capacity of the adsorption column is calculated to obtain the first ratio at any time. For the desorption column, the ratio of the xenon migration amount at any time to the maximum desorption capacity of the desorption column is calculated to obtain the second ratio at any time. The product of the first ratio and the pressure change index is calculated as the xenon migration index of the adsorption column at any time. Based on the second ratio and the pressure change index, the xenon migration index of the desorption column at any time is obtained through a preset index calculation function.

[0085] It should be noted that if the sieve size in the dual molecular sieve tower is the same and the adsorption and desorption are reversible processes, then the maximum adsorption capacity and the maximum desorption capacity are equal. The methods for obtaining the maximum adsorption capacity and the maximum desorption capacity are well known to those skilled in the art, and will not be described in detail in this embodiment.

[0086] It should be noted that the maximum adsorption capacity refers to the maximum amount of xenon that a unit mass or volume of molecular sieve can adsorb under specific conditions (including but not limited to set temperature, set pressure, and initial xenon concentration). This value is the upper limit of the molecular sieve's adsorption capacity for xenon. When the adsorbent reaches its maximum adsorption capacity, its adsorption of xenon reaches saturation, and continuing to introduce gas will no longer significantly increase the adsorption amount, that is, the adsorption rate approaches 0.

[0087] The first ratio is used to quantify the degree of xenon adsorption saturation of the sieve material in the adsorption tower under ideal conditions at a certain moment.

[0088] The second ratio is used to quantify the degree of xenon desorption saturation of the screen material in the desorption tower under ideal conditions at a certain moment.

[0089] Because increased pressure enhances the adsorption capacity of the sieve material within the molecular sieve tower for xenon, thus increasing the adsorption amount; a higher first ratio at a given moment reflects a stronger adsorption capacity of the sieve material for xenon within the adsorption tower. Therefore, assuming When the xenon migration index of the adsorption tower exceeds the preset adsorption threshold, it can be expressed by the following formula:

[0090]

[0091] in, This represents the xenon migration index of the adsorption tower at time i. ,in, This represents the first ratio of the adsorption tower at time i; This represents the amount of xenon gas that migrates in the adsorption tower at time i. Indicates the maximum adsorption capacity; This indicates an indicator of pressure change.

[0092] It should be noted that xenon migration refers to the change in the amount of xenon gas within the molecular sieve tower due to adsorption or desorption processes. In actual operation of the molecular sieve tower, even if the adsorption or desorption of xenon gas in the sieve material is close to saturation, there will still be changes in xenon gas levels. Moreover, the alternating switching of adsorption and desorption modes in the dual molecular sieve tower will result in xenon migration. Therefore, at any given moment during the operation of the molecular sieve tower, the amount of xenon gas adsorbed and desorbed cannot be zero, and the maximum adsorption capacity and maximum desorption capacity also cannot be zero.

[0093] Since a decrease in pressure increases the desorption capacity of the sieve material in the molecular sieve tower for xenon, thus increasing the desorption amount; and if the second ratio is larger at a certain moment, it reflects a stronger desorption capacity of the sieve material in the desorption tower for xenon, therefore, assuming If the xenon migration index of the desorption tower at any given time is less than the preset adsorption threshold, it can be represented by the following preset index calculation function:

[0094]

[0095] in, This represents the xenon migration index of the desorption tower at time i; in, This represents the second ratio of the desorption tower at time i; This represents the amount of xenon gas that migrates in the desorption tower at time i. This represents the maximum desorption capacity of the desorption tower at time i.

[0096] Step S102: Determine the switching urgency of each molecular sieve tower at any given time based on the gas concentration change characteristics and feed flow rate fluctuation characteristics; generate a comprehensive switching degree based on the xenon migration index and the switching urgency.

[0097] It should be noted that the overall switching degree is used to quantify the necessity of switching modes in the dual molecular sieve tower.

[0098] It is important to understand that the xenon migration index can be used to understand the degree of xenon adsorption or desorption within the tower at different times. However, the purpose of this embodiment is to explore the appropriate switching time for the dual molecular sieve tower. Ideally, the switching should be performed when both the adsorption and desorption degrees of the dual towers reach their maximum. However, since the feed rate of the mixed gas is constantly changing, and the adsorption and desorption capacity of the sieve material also changes with the operation of the device, in order to explore the appropriate switching time for the dual molecular sieve tower, it is also necessary to combine the fluctuation characteristics of the feed rate of the mixed gas and the gas concentration change characteristics to determine the appropriate switching time.

[0099] In this embodiment, for the adsorption tower, the standard output concentration of other gases in the tower, the first gas concentration when other gases exit the adsorption tower, and the second gas concentration when other gases enter the adsorption tower are obtained at any given time. For the desorption tower, the third gas concentration when xenon gas exits the desorption tower and the fourth gas concentration when xenon gas enters the desorption tower are obtained at any given time. Based on the standard output concentration, the first gas concentration, and the second gas concentration, a first switching evaluation score for the adsorption tower at any given time is obtained through a preset scoring function. The absolute difference between the third gas concentration and the fourth gas concentration is calculated, and the negative of the absolute difference is used as the second switching evaluation score for the desorption tower at any given time. The feed flow rate of the mixed gas in each molecular sieve tower at any given time is compared with the feed flow rate of the mixed gas in the previous adjacent time to obtain the flow rate change rate of each molecular sieve tower at any given time. The product of the first switching evaluation score and the flow rate change rate of the adsorption tower is calculated as the switching urgency of the adsorption tower. The product of the second switching evaluation score and the flow rate change rate of the desorption tower is calculated as the switching urgency of the desorption tower.

[0100] It should be noted that the switching urgency reflects the degree to which the state inside the molecular sieve tower deviates from the optimal operating point under the current mode.

[0101] It should be noted that "other gases" is used to indicate gases other than xenon in the gas mixture.

[0102] It should be noted that the switching urgency of the adsorption tower is obtained by calculating the first switching evaluation score and the flow rate change rate of the adsorption tower at the same time; and the switching urgency of the desorption tower is obtained by calculating the second switching evaluation score and the flow rate change rate of the desorption tower at the same time.

[0103] It is important to understand that for a molecular sieve tower in adsorption mode, when a mixed gas enters the tower, xenon is adsorbed, and other gases flow out, the concentration of xenon will gradually decrease. As adsorption proceeds, the packing density of the sieve molecules increases, leading to a decrease in its adsorption capacity. Consequently, the purity of other gases will also decrease, resulting in a reduction in the adsorption capacity of the molecular sieve tower. Therefore, it is necessary to switch to desorption mode in a timely manner.

[0104] It should be noted that the standard output concentration is the result of calculating or converting the concentration of other gases in the substance discharged from the adsorption tower outlet under a unified standard condition. The method of obtaining the standard output concentration is a well-known technical means in the art, and will not be described in detail in this embodiment. For example, the concentration of other gases discharged from the adsorption tower outlet at a certain moment is converted to the concentration under standard conditions (0℃, 101.325kPa).

[0105] It should be noted that the standard state may have different subtle definitions in different industries, and the specific content of the standard state is determined according to the actual situation. This embodiment does not make specific limitations.

[0106] For a molecular sieve tower in adsorption mode, a larger difference between the standard output concentration and the concentration of the first gas indicates that the purity of other gases is further away from the standard purity, meaning the adsorption capacity of the sieve material in the tower is weaker. Conversely, a smaller absolute difference between the concentrations of the first and second gases indicates that the concentration differences of other gases after passing through the adsorption tower are smaller, meaning the purity of other gases is closer to the concentration in the mixed gas, resulting in weaker adsorption capacity. The weaker the adsorption capacity, the higher the urgency for the adsorption tower to switch modes. Therefore, the first switching evaluation score of the adsorption tower at any given time can be represented by the following preset score calculation function:

[0107]

[0108] in, This represents the evaluation score of the adsorption tower at time i; This represents the standard output concentration of other gases in the adsorption tower at time i; This represents the first gas concentration in the adsorption tower at time i; represents the concentration of the second gas in the adsorption tower at time i; | represents taking the absolute value.

[0109] It should be noted that, ideally, the concentrations of the first and second gases would be the same. However, in actual operating conditions, the sieve material inside the adsorption tower cannot completely prevent the adsorption of other gases. Furthermore, due to factors such as temperature and pressure within the tower, other gases flowing into the adsorption tower cannot be completely expelled. It cannot be zero.

[0110] It's important to understand that in a desorption tower, xenon gas enters through the adsorption tower, while the desorption tower itself releases xenon gas through depressurization. The two gases mix before being output. Therefore, if the concentration difference between the xenon gas entering and leaving the desorption tower at a given moment is smaller, it indicates that the desorption tower's desorption capacity is weaker.

[0111] Since a smaller absolute difference between the concentrations of the third and fourth gases at a given moment indicates a weaker desorption capacity of the desorption tower, thus necessitating a more urgent mode switching, the second switching evaluation score of the desorption tower at any given moment can be expressed by the following formula:

[0112]

[0113] in, This represents the second switching evaluation score of the desorption tower at time i; This represents the concentration of the third gas in the desorption tower at time i; represents the fourth gas concentration in the desorption tower at time i; | represents taking the absolute value.

[0114] It should be noted that, under actual operating conditions, even if the desorption capacity of the screen material inside the desorption tower gradually approaches saturation, the screen material inside the desorption tower cannot completely stop desorbing xenon. Furthermore, due to factors such as temperature and pressure inside the tower, the xenon cannot be completely discharged from the desorption tower. It cannot be zero.

[0115] It is important to understand that the feed rate of the mixed gas may change during the process of separating and purifying xenon. However, if the feed rate is increased while the adsorption and desorption rates of the sieve material remain unchanged, the mode of the bimolecular sieve tower needs to be switched in advance to ensure good purification results in order to avoid excessive accumulation or retention.

[0116] Since the feed rate of the mixed gas at a certain moment is larger than that at the previous moment, it indicates that the feed rate of the mixed gas has increased. In this case, excessive accumulation or stagnation of the mixed gas may occur, requiring an increase in the switching frequency of the bimolecular sieve tower. Therefore, the rate of change of flow rate can be expressed by the following formula:

[0117]

[0118] in, This represents the rate of change of the flow rate in the molecular sieve column at time i. This represents the feed flow rate of the mixed gas in the molecular sieve column at time i. represents the feed rate of the mixed gas in the molecular sieve tower at time i-1; | represents taking the absolute value.

[0119] It should be noted that if there is no feed flow rate of the mixed gas at the first time and the zeroth time immediately preceding it, the rate of change of flow rate is set to 1. In actual operation, the anesthetic mixed gas will only be stopped when the device stops running or malfunctions. Therefore, the feed flow rate of the mixed gas cannot be zero when the device is running normally.

[0120] Since a larger rate of change in flow rate indicates a faster feed flow rate of the mixed gas, the switching frequency of the bimolecular sieve tower needs to be increased; and a higher first switching evaluation score of the adsorption tower at a certain moment indicates a higher urgency for the adsorption tower to switch modes, the switching urgency of the adsorption tower can be expressed by the following formula, taking the adsorption tower as an example:

[0121]

[0122] in, This indicates the urgency of switching the adsorption tower at time i; This represents the evaluation score of the adsorption tower at time i; This represents the rate of change of the flow rate in the adsorption tower at time i.

[0123] It should be noted that since the calculation method for the switching urgency of the desorption tower is the same as that for the adsorption tower, only the input parameters are different, the specific calculation method for the switching urgency of the desorption tower will not be described in this embodiment.

[0124] It should be noted that after obtaining the switching urgency of the adsorption tower and the switching urgency of the desorption tower, in order to eliminate the differences in dimensions and magnitudes, the switching urgency of the adsorption tower and the switching urgency of the desorption tower need to be normalized.

[0125] It is important to understand that after determining the urgency of switching and the xenon migration index, in order to achieve the best purification effect of xenon by the device, multiple factors can be considered, such as the characteristics of gas concentration change, the characteristics of feed flow rate fluctuation, and the degree of adsorption or desorption of xenon by the sieve material in the tower. By understanding the urgency of switching and the xenon migration index, we can gain a deeper understanding of the necessity and urgency of switching the mode of the dual molecular sieve tower at any given time.

[0126] In this embodiment, the sum of the positive integer 1 and the switching urgency of the adsorption tower is calculated as the first weight; the sum of the positive integer 1 and the switching urgency of the desorption tower is calculated as the second weight; the product of the xenon migration index and the first weight is calculated as the comprehensive switching degree of the adsorption tower at any time; the product of the xenon migration index and the second weight is calculated as the comprehensive switching degree of the desorption tower at any time.

[0127] Since a higher urgency in switching the molecular sieve tower at a given moment indicates a greater necessity and urgency for switching modes at that moment, and a higher xenon migration index at a given moment indicates that the adsorption or desorption of xenon within the molecular sieve tower will approach saturation, the overall switching degree of the adsorption tower at any given moment can be expressed by the following formula, taking the adsorption tower as an example:

[0128]

[0129] in, This represents the overall switching degree of the adsorption tower at time i; This represents the xenon migration index of the adsorption tower at time i. This indicates the urgency of switching the adsorption tower at time i.

[0130] It should be noted that since the calculation method for the overall switching degree of the desorption tower is the same as that of the adsorption tower, only the input parameters are different, the specific calculation method for the overall switching degree of the desorption tower will not be described in this embodiment.

[0131] Step S103: Monitor the trend of the overall switching degree over time in real time and determine the rate of change; when the rate of change is lower than the preset convergence threshold for the first time, it is determined to be the optimal switching time.

[0132] It is important to understand that after a certain switching of the dual molecular sieve tower, as the adsorption of xenon by the sieve material in the adsorption tower and the desorption of xenon by the sieve material in the desorption tower proceed, the adsorption and desorption capacity of the sieve material in the molecular sieve tower will gradually become saturated over time. As time changes, the overall switching degree will also tend to converge. The moment when the overall switching degree converges is the optimal switching time for the dual molecular sieve tower.

[0133] In this embodiment, the absolute difference between the comprehensive switching degree of the adsorption tower at any given time and the comprehensive switching degree of the adsorption tower at the previous adjacent time is calculated as the first difference of the adsorption tower at the corresponding time; the absolute difference between the comprehensive switching degree of the desorption tower at any given time and the comprehensive switching degree of the desorption tower at the previous adjacent time is calculated as the second difference of the desorption tower at the corresponding time; the product of the first difference and the second difference at the same time is calculated as the rate of change, wherein the value of the rate of change is a normalized value.

[0134] It should be noted that the specific value of the preset convergence threshold is determined according to the actual situation, and this embodiment does not impose a specific limitation. For example, when the preset convergence threshold is 0.2, when the rate of change at a certain moment is first lower than 0.2, the moment is determined to be the optimal switching moment. Switching the dual molecular sieve tower mode at this moment can reveal that the device has a better xenon purification effect.

[0135] As a specific implementation, the xenon recovery and purification device for anesthetic mixed gas also includes a purity determination module. While ensuring that the normal flow of gas inside the xenon recovery and purification device for anesthetic mixed gas is not affected, the purity determination module is placed as close as possible to the desorption tower outlet area. The purity determination module is used to monitor the composition concentration of the gas at the outlet of the desorption tower in real time. When the xenon concentration in the outlet gas is not less than the preset xenon concentration threshold and the oxygen concentration is not greater than the preset oxygen impurity threshold, the xenon purification of the xenon recovery and purification device is determined to be complete.

[0136] It should be noted that the specific values ​​of the preset xenon concentration threshold and the preset oxygen impurity threshold are determined according to actual needs, and this embodiment does not impose specific limitations. For example, the preset xenon concentration threshold is usually set to 99.995%, and the preset oxygen impurity threshold is usually set to 5 ppm (parts per million), where 99.995% is a volume fraction.

[0137] An intelligent control system for the recovery and purification of xenon gas in an anesthetic gas mixture is disclosed. The intelligent control system includes a memory, a processor, and a computer program stored in the memory and running on the processor. When the processor executes the computer program, it implements the steps of the xenon gas recovery and purification device for the anesthetic gas mixture.

[0138] It should be noted that the order of the above embodiments of the present invention is merely for descriptive purposes and does not represent the superiority or inferiority of the embodiments. The processes depicted in the accompanying drawings do not necessarily require a specific or sequential order to achieve the desired result. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0139] The various embodiments in this specification are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. The focus of each embodiment is to describe the differences from other embodiments.

Claims

1. A xenon recovery and purification apparatus for anesthetic gas mixtures, characterized in that, The xenon recovery and purification device comprises two parallel molecular sieve towers, wherein the double molecular sieve towers are alternately switched between adsorption mode and desorption mode during operation, and the device comprises: a data acquisition module for acquiring gas state data of each molecular sieve tower in real time, wherein the gas state data comprises tower internal pressure, gas concentration and feed flow rate; a processing control unit for determining xenon migration amount of each molecular sieve tower at any time based on the tower internal pressure by using an adsorption isotherm model; determining xenon migration index of each molecular sieve tower at any time according to pressure change characteristics and the xenon migration amount of each molecular sieve tower at any time, wherein the xenon migration index is used to represent the adsorption or desorption degree of xenon in the tower; determining switching urgency of each molecular sieve tower at any time according to gas concentration change characteristics and feed flow rate fluctuation characteristics; generating comprehensive switching degree according to the xenon migration index and the switching urgency; monitoring the change trend of the comprehensive switching degree with time in real time to determine the change rate; and determining the best switching time when the change rate is first lower than a preset convergence threshold; a switching module for triggering mode switching of the double molecular sieve towers at the best switching time; the device further comprises: acquiring initial time when each molecular sieve tower just enters the adsorption mode or the desorption mode and initial pressure in the tower of each molecular sieve tower at the initial time; calculating the ratio of the tower internal pressure of each molecular sieve tower at any time to the initial pressure at the target initial time to obtain pressure change index of each molecular sieve tower at any time, wherein the target initial time is used to indicate the initial time with the shortest time interval from any time; if the pressure change index exceeds a preset adsorption threshold, it is determined that the corresponding molecular sieve tower is in the adsorption mode, and the molecular sieve tower in the adsorption mode is referred to as an adsorption tower; if the pressure change index is less than the preset adsorption threshold, it is determined that the corresponding molecular sieve tower is in the desorption mode, and the molecular sieve tower in the desorption mode is referred to as a desorption tower; the xenon migration amount determination process comprises: acquiring the gas partial pressure of xenon in the tower of each molecular sieve tower; for the adsorption tower, calculating xenon adsorption amount of the adsorption tower at any time by using the adsorption isotherm model based on the gas partial pressure of xenon in the tower; and taking the xenon adsorption amount as the xenon migration amount of the adsorption tower; for the desorption tower, calculating xenon desorption amount of the desorption tower at any time by using the adsorption isotherm model based on the gas partial pressure of xenon in the tower; and taking the xenon desorption amount as the xenon migration amount of the desorption tower; the xenon migration index determination process comprises: acquiring the maximum adsorption capacity and the maximum desorption capacity of each molecular sieve tower; for the adsorption tower, performing ratio operation on the xenon migration amount of the adsorption tower at any time and the maximum adsorption capacity of the adsorption tower to obtain a first ratio of the adsorption tower at any time; and for the desorption tower, performing ratio operation on the xenon migration amount of the desorption tower at any time and the maximum desorption capacity of the desorption tower to obtain a second ratio of the desorption tower at any time; calculating the product of the first ratio and the pressure change index as the xenon migration index of the adsorption tower at any time; obtaining the xenon migration index of the desorption tower at any time by a preset index calculation function based on the second ratio and the pressure change index; the switching urgency determination process comprises: For the adsorption tower, the standard output concentration of other gas in the tower at any time, the first gas concentration of the other gas flowing out of the adsorption tower, and the second gas concentration of the other gas entering the adsorption tower are obtained; for the desorption tower, the third gas concentration of xenon gas flowing out of the desorption tower at any time and the fourth gas concentration of xenon gas entering the desorption tower are obtained, wherein the other gas is used to indicate other gas in the mixed gas except xenon gas; Based on the standard output concentration, the first gas concentration and the second gas concentration, a first switching evaluation score of the adsorption tower at any time is obtained by a preset score calculation function; The absolute difference between the third gas concentration and the fourth gas concentration is calculated, and the reciprocal of the absolute difference is taken as the second switching evaluation score of the desorption tower at any time; The feed flow rate of the mixed gas of each molecular sieve tower at any time is ratio-operated with the feed flow rate of the mixed gas at the previous adjacent time, and the flow rate change rate of each molecular sieve tower is obtained; The product of the first switching evaluation score and the flow rate change rate of the adsorption tower is calculated as the switching urgency of the adsorption tower; the product of the second switching evaluation score and the flow rate change rate of the desorption tower is calculated as the switching urgency of the desorption tower; The comprehensive switching degree determination process comprises: The sum of the positive integer 1 and the switching urgency of the adsorption tower is calculated as a first weight; the sum of the positive integer 1 and the switching urgency of the desorption tower is calculated as a second weight; The product of the xenon migration index and the first weight is calculated as the comprehensive switching degree of the adsorption tower at any time; the product of the xenon migration index and the second weight is calculated as the comprehensive switching degree of the desorption tower at any time.

2. The xenon recovery and purification apparatus for anesthetic gas mixture according to claim 1, characterized by The change rate determination process comprises: The absolute difference between the comprehensive switching degree of the adsorption tower at any time and the comprehensive switching degree of the adsorption tower at the previous adjacent time is calculated as a first difference value of the adsorption tower at the corresponding time; The absolute difference between the comprehensive switching degree of the desorption tower at any time and the comprehensive switching degree of the desorption tower at the previous adjacent time is calculated as a second difference value of the desorption tower at the corresponding time; The product of the first difference value and the second difference value at the same time is calculated as the change rate, wherein the numerical value of the change rate is a normalized numerical value.

3. The xenon recovery and purification unit for use in mixing anesthetic gas according to claim 1, characterized by The switching module further comprises: At the optimal switching time, the adsorption mode and the desorption mode of the double molecular sieve towers are exchanged by gradually adjusting the pressure and controlling the intake valve to switch the mixed gas flow direction.

4. The xenon recovery and purification unit for use in mixing anesthetic gas according to claim 1, characterized by The device further comprises: The composition concentration of the outlet gas of the desorption tower is monitored in real time, and when the xenon concentration in the outlet gas is not less than a preset xenon concentration threshold and the oxygen concentration is not greater than a preset oxygen impurity threshold, it is determined that the xenon purification of the xenon recovery and purification device is completed.

5. An intelligent control system for xenon recovery purification of anesthetic gas mixture, characterized in that, The intelligent control system comprises a memory, a processor, and a computer program stored in the memory and running on the processor, and the processor implements the steps of the device according to any one of claims 1-4 when executing the computer program.

Images